The six species of the Juglandaceae which have been considered possess well developed lateral sieve plates which have the same structure and appearance and seem to function in the same manner as the sieve plates on the end walls. The callus on the lateral sieve plates is identical in character with that on the end walls. The large sieve tubes have lateral sieve plates which are as crowded and as large as the terminal ones. This is contrary to the accepted views in regard to the sieve tubes of the dicotyledons. It would seem that we have here to do with an ancestral character, which indicates that the lower dicotyledons, as exemplified in the Juglandaceae, are more nearly related to the gymnosperms or vascular cryptogams. It is hoped that a further study of the phloem of the dictoyledons may disclose other ancestral traits, or aid somewhat in a systematic classification from an anatomical standpoint.